The instant invention relates to the removal of volatile components from thermoplastic polymers and more specifically to methods and apparatus therefore that use centrifugal force.
Chisholm, U.S. Pat. No. 3,409,712, herein fully incorporated by reference, disclosed a method and apparatus for devolatilization of thermoplastic polymers by melting the polymer and flowing the melted polymer on a rotating disk surface. Chisholm, U.S. Pat. No. 3,424,832, herein fully incorporated by reference, disclosed a method and apparatus for pelletizing a thermoplastic polymer using a rotating chamber or hollow rotor. Hay, II et al., U.S. Pat. No. 4,940,472, herein fully incorporated by reference, disclosed a method and apparatus for devolatilization of thermoplastic polymers by melting the polymer and flowing the melted polymer on a rotating disk surface. Moore et al., U.S. Pat. No. 4,952,672, herein fully incorporated by reference, disclosed a method and apparatus for devolatilization of thermoplastic polymers by melting the polymer and flowing the melted polymer on a rotating disk surface. Baker Perkins Incorporated of Saginaw Michigan offered a centrifugal pelletizer for sale. Modern Plastics, December 1983, page 56. Haw, Master's Thesis, Case Western Reserve University, January 1995, entitled "Mass Transfer of Centrifugally Enhanced Polymer Devolatilization by using Foam Metal Packed Bed", herein fully incorporated by reference, disclosed a method and apparatus for devolatilization of thermoplastic polymers by melting the polymer and flowing the melted polymer through a open-cell nickel metal foam gas-liquid contactor rotated within a stationary chamber.
The method and apparatus of Haw suffered from several problems. For example, the nickel metal foam tended to collapse under the centrifugal forces to which it was subjected. In addition, the mechanical seal used tended to contaminate the devolatilized polymer with the seal oil. Furthermore, the method and apparatus of Haw did not produce the devolatilized polymer in the form of pellets.